In general, an electric field emission device means a device where electrons are emitted from a surface of metal or semiconductor in a vacuum in accordance with tunneling effect caused by applying electronic field having high intensity to the surface. Such an electric field emission device may be utilized as a high-speed switching device, a microwave generator, an amplifier or a display device. In the device, the emitted electrons can induce high power at a high frequency in a vacuum with low energy loss. Further, the device has several advantages that it has a shorter response time than a conventional solid-state device and may be integrated on a single silicon chip.
FIG. 1 illustrates a cross-sectional view of a conventional “Spindt” type electric field emission device having a triode structure fabricated by using an electron beam photolithographic process.
Referring to FIG. 1, the electric field emission device is fabricated as follows. That is, on a glass or a silicon substrate 100, a cathode layer 102, a resistive layer 104, an insulating layer 106 and a gate electrode layer 108 are formed sequentially. And then, photosensitive film patterns, each having a diameter of micrometer, are formed on the gate electrode 108 by using a photolithographic process. Thereafter, the insulating layer 106 is etched by using a reactive ion etching technique such that a surface of the resistive layer 104 is exposed. Subsequently, a metal electric field emission tip 110 containing material such as Mo, W and Cr is vertically deposited on the resistive layer 104 to have a conical shape by using an electron beam evaporation technique.
As mentioned above, the Spindt type electric field emission device has advantages that it has a shorter response time than a conventional solid-state device and may be integrated on a single silicon chip. However, it is difficult to arrange a plurality of micro holes at regular intervals on the electric field emission device as shown in FIG. 1, particularly when an area of the surface of the device is large. Further, since a distance between an electric field emission tip and an anode electrode is several hundreds micrometers, the electric field emission device as shown in FIG. 1 has a disadvantage that it requires a high driving voltage. Furthermore, there may be needed an additional process to form micro holes, each having a sub-micrometer diameter, on the surface of the gate electrode layer 108.